blender script startup fail
If you come across a problem like this, the solution might be not to copy&amp;paste from an existing exporter script, but to literally copy the directory of some such exporter into .config/blender/x.xx/scripts/addons and work on it from there. This seems to work, but the root cause was blender getting freaked out by my bl_info line. Specifically:

bl_info = {
...
"support": 'NONE',
...
}


freaked it out and omitting the line solved the issue.